Tackling Spice-Processing Wastewater: Innovative Processes and Technology in Action
Spices are widely used in food manufacturing, daily chemicals and many other fields. The wastewater generated during spice production contains large quantities of aromatic hydrocarbons, aromatic compounds and their derivatives — more than twenty constituents in total — including phenols, toluene and benzaldehyde, substances that inhibit microbial activity. In addition, large amounts of surfactants are often added during reactor cleaning and similar operations. Such wastewater is therefore characterized by high pollutant concentrations, large water-quality fluctuations, strong biological inhibition and complex composition, and can hardly be treated directly by biochemical processes, making it one of the more difficult categories of industrial wastewater to treat.
Because spice-production wastewater has low biodegradability, pretreatment is usually required in practice. Optional pretreatment methods include micro-electrolysis, micro-electrolysis–catalytic oxidation, wet oxidation and ozone oxidation. The specific process can be selected according to the results of bench-scale tests.
After pretreatment improves its biodegradability, the wastewater enters an equalization tank to balance water quality and quantity, and then proceeds to the biochemical treatment stage, which is generally arranged in sequence as anaerobic treatment, denitrification, organic matter degradation and nitrification.
To meet the special needs of spice-production wastewater treatment, SINOKLE Technology relies on its independently developed CDOF (Cyclonic Dissolved Ozone Flotation) technology, which can effectively reduce the chemical oxygen demand (COD) of the wastewater and improve its biodegradability, creating favorable conditions for subsequent biochemical treatment.
CDOF process flow diagram
The diagram shows the working process of the CDOF system. CDOF (Cyclonic Dissolved Ozone Flotation unit) innovatively integrates ozone advanced oxidation technology, cyclonic separation technology and dissolved-air flotation technology to achieve efficient comprehensive purification of various refractory wastewaters.
This ozone catalytic oxidation process features a short flow, simplified equipment, compact units and a small footprint. With few electric devices, low energy consumption and economical operating costs, it is easy to operate and can be automatically controlled, reducing dependence on on-site operators. When influent quality and quantity fluctuate, the system has strong regulation capability and excellent shock-load tolerance. It can also be combined with other technologies (such as biochemical methods) to give full play to their respective advantages and further improve overall treatment performance.
Micro-Nano Bubble Technology
The ultra-fine micro-nano bubble generation technology centers on a micro-nano bubble generation system whose core equipment performs efficient gas dissolution, release and mixing. Micro-nano bubbles are extremely small bubbles with diameters below 50 microns. They rise slowly in water, stay longer and dissolve efficiently, and possess unique properties such as self-increasing oxygen content, negatively charged surfaces and an abundance of strongly oxidizing free radicals.
Bench-scale experimental data for a spice-processing wastewater
Experimental conclusion: when treated with this process at an ozone dosage of 150 mg/L, the effluent COD dropped to 238.8 mg/L, with a COD removal of 186.55 mg/L and an ozone consumption ratio of 0.80. The results show that the process oxidizes and decomposes part of the macromolecular COD into small-molecule COD, not only removing part of the pollutants but also effectively improving the biodegradability of the wastewater, laying a solid foundation for the subsequent biochemical treatment stage.
